Interferon alpha as monotherapy or combination therapy for chronic hepatitis B

Abstract

The hepatitis B virus (HBV) is a DNA virus that belongs to the group ofhepadnaviridae. The partially double-stranded DNA contains 4 open reading frames, encoding for the envelope (pre-S/ S), core (precore/ core), polymerase and X proteins. The pre-S/S open reading frame encodes for the large, middle and small surface glycoproteins. The precore/ core region encodes for both the nucleocapsid protein (hepatitis B core antigen) and a soluble protein, the hepatitis B e antigen (HBeAg). After attachment of HBV to the hepatocyte, the viral genome is converted into covalently closed circular DNA (cccDNA) within the hepatocyte nucleus (Figure 1). This cccDNA serves as template for the pregenomic mRNA. In the hepatocyte cytoplasm viral particles are assembled from HBV core protein, HBV DNA polymerase and the pregenomic mRNA. Within these particles the pregenomic mRNA is reverse transcribed by the HBV DNA polymerase into the minus strand HBV DNA. Finally the plus strand DNA is synthesized by the HBV DNA polymerase. There are seven major HBV genotypes (A to G), prevailing in different parts of the world. Recently another genotype, genotype H, was found in central America.